Level shifters are used to change a signal voltage level between the input/output (I/O) device voltage, e.g., 3.3V, to the core device voltage, e.g., 0.9V. In some approaches, the level shifters are formed using I/O devices. The I/O devices have a thicker gate dielectric layer in comparison with the core devices to withstand higher voltages.
In some approaches, the level shifters increase a voltage level of a logically high voltage from a first level to a second higher level. In some approaches, these level shifters do not increase a voltage level of a logically low voltage. The level shifters which maintain a same logically low voltage level increase a voltage swing of an output signal in comparison with an input signal. In some approaches, the level shifters include a bias circuit to increase the logically low voltage level.
In some approaches, the level shifters are formed using devices similar to the core devices. The core devices have a thinner gate dielectric than the I/O devices. As a result, a voltage swing which is able to damage the core devices has a smaller range with respect to the I/O devices.